It is known to provide a two-stage power management topology for battery-powered devices. An example of this is shown in FIG. 1 where a power management circuit comprises a switching charger integrated circuit 100 and a DC-DC power management integrated circuit 102. The switching charger 100 comprises a buck converter and is optimised for efficient charging of a battery 104. The DC-DC power management integrated circuit 102 comprises a buck-boost converter and is optimised for providing a regulated system voltage to a device.
Each of the dedicated integrated circuits 100, 102 makes use of its own inductor. Switching converters have good power efficiency compared with linear converters. For example, a typical buck converter 100 and buck-boost converter 102 may each operate with an efficiency of around 95% in which case the total system efficiency may be around 90%.
However, having two separate power conversion stages results in more electromagnetic interference and noise as compared with single stage topologies.